The present invention relates to a method of forming an insulating film. More particularly, the invention relates to an insulating film suitably used as an interlayer dielectric for a semiconductor device or the like, a method of forming the same, and a film-forming composition.
A silica (SiO2) film formed by a vacuum process such as a chemical vapor deposition (CVD) method has been widely used as an interlayer dielectric for a semiconductor device or the like.
In recent years, in order to form an interlayer dielectric having a more uniform thickness, a spin-on-glass (SOG) film, which is a coating-type insulating film containing a tetraalkoxysilane hydrolysate as the major component, has also been used. Along with an increase in the degree of integration of a semiconductor device, a low-relative-dielectric-constant interlayer dielectric called an organic SOG containing a polyorganopolysiloxane as the major component has been developed.
However, more excellent electrical insulation between conductors has been demanded accompanying a further increase in the degree of integration and multilayering of a semiconductor device. Therefore, an interlayer dielectric having an excellent storage stability and a lower relative dielectric constant (low-k) and exhibiting superior leakage current characteristics has been in demand.
When forming an Si-containing film, such as SiO2, SiN, SiC, SiCN, or SiOC, on a low-k insulating film represented by a polysiloxane insulating film by using a plasma CVD method, the low-k insulating film may be damaged due to plasma generated during deposition. If the insulating film is damaged, the relative dielectric constant of the insulating film is increased, or the insulating film exhibits decreased resistance against processing such as etching, ashing, or wet cleaning.